WS4

Fuel Pressure and flow ( Petrol only)


Make of vehicle  Nissan  Model  Primera 


1. Located the two closes if you have to use it remember to pull the pin, squeeze the handle and spray at the base of the flame.) Write down where they are:
I used shed (work shop)

2.0 If you look up fuel pressure specifications for the vehicle you are testing . If you cant look them up, make a guess at the fuel specs you should have and write them down here:   265 - 304 kpa.

3.0 use eye protection Optional: Relieve fuel pressure before installing pressure gage. there is some instruction and method i follow them.


4.0 Attach fuel pressure gage and notice which scale on the gauge you will be using. Turn on or start the engine the urn off, check for fuel leak: NO leaks.


5.0 Measure the fuel pressure with the key on, engine off.
Record it here 270 kpa

6.0 Idling: Measure the fuel pressure with the engine idling. W hatch the pressure for a couple a minutes.
Record of pressure: 275 kpa

7. Maximum: With the idling, use the special tool to clamp the fuel return line.

Record pressure here: 480 kpa.


8. Wot: with the engine idling, disconnect and plug the vacuum line going to the fuel pressure regulator.

Record pressure here: 320 kpa


9. Residual: Turn off the engine, and watch the fuel pressure for five minutes.
Record your residual or rest pressure here: 250 kpa.

10.Flow: Hook up proper equipment to read fuel volume if necessary.Record flow gauge results of volume, or how much pumped in 15 seconds: (normal results may be 1/2 liter in 15 seconds)  1.5 L

11.Replace vacuum lines.and remove the pressure gauge line, and turned the engine on and off check for leaks there is NO leaks.

12. Enplane why it is important to know a vehicle fuel pressure/flow?
Fuel pressure is clerical for smooth functioning of an engine it is the fuel pressure in the fuel rail, that fuel injectors  sprayed fuel according to the engine loads and speed and for the best combustion of power and effecincy.

13.Describe the symptoms a vehicle would give with each case.
Low fuel pressure.
Low pressure make the engine run lean, may take long time to start, it may misfire, hesitate, or halt

Low fuel flow
Misfire, halt, hesitation.

High fuel pressure
High pressure can cause an engine run rich the increasing the emission from the vehicle and may be cause clogging, misfiring,or racing.

Faulty fuel pressure regulator
The engine may run rich because of high fuel pressure in the fuel rail or may run lean due to low pressure and for both of these problems. that above symptoms may be detected as fuel pressure regulator (faulty) which can not work with fuel pump to maintain a steady pressure relationship between the fuel line side of the injectors and intake manifold.